Inclined plates are commonly used in settling devices for settling tanks to increase settling area and thereby capacity to clarify liquid.
The liquid, most often water, to be treated is distributed, together with its contents of undesired suspended solids, from an influent channel to liquid lamellas which are formed between the inclined plates. It flows upwardly during settling of the suspended solid particles and subsequently reaches an overflow for clarified liquid.
The increase in capacity of settling tanks with inclined plates is due to the fact that the particles only have to move the short vertical distance to the lower plate in the liquid lamella in order to be separated. When the particles have reached the inclined plates they will slide down along the plates into a sludge holding volume which is positioned below the inclined plates. From there sludge is normally transported by a scraper or by gravity to a sludge hopper which it leaves as an underflow.
There are many configurations of inclined plate settling devices put on the market. The commercially most important ones are of the counter-current type i.e. the liquid under treatment flows upwards in the liquid lamellas while the settled out solids slide down the plates in counter-current to the liquid flow.
There exist two main types of counter-current inclined plate settling devices:                a. A first type having the inclined plates totally submerged in the liquid with outlet means for the clarified liquid at a level above the plates.        b. A second type having the upper portion of each inclined plate sticking out above the water level. In this case the clarified water runs sideways over a weir (weirs) into an effluent flume(-s) at a level below the top of the plates.        
Both types can be constructed as plate packs for inclusion in concrete, plastic or steel tanks. Type a. devices are normally built and assembled in a workshop and shipped to the point of use, whereas the effluent flume/feed channel combination of the b. type settling device is built and assembled in a workshop and shipped to the point of use where it is mounted inside a concrete tank by bolting it to anchoring pieces in the concrete walls. The plates are then mounted inside the tank one by one at site.
Inclined plate settling devices have basically been built in the same way for more than 20 years. Because of the complexity of making and installing prior art settling devices, there is a great need and demand for a simpler, more cost-effective inclined plate settling device.